Interaction of Anti-G Measures and Chest Wall Mechanics in Determining Gas Exchange.
Abstract
During the last twelve months, progress has been made in three experimental areas: (1) determination that right ventricular blood provides an accurate mixed venous blood sample in the canine; (2) investigation of gas exchange during repeated canine +Gz exposures; and (3) characterization of pressure-volume relationships of the pig lung and chest wall. It is generally assumed that pulmonary arterial blood best represents mixed venous blood. Under some conditions (e.g., during +Gz stress) sampling from this site is difficult. To determine if the right ventricle is as good a sampling site as the pulmonary artery in the dog, samples were drawn from both sites and compared for blood gas composition. No physiologically significant differences were detected between the two sites in this species. Results of our earlier studies indicated that exposure to +Gz stress in the presence of G-suit abdominal bladder inflation and breathing air leads to a gas exchange detriment lasting as long as three minutes post-exposure. To determine if this detriment is cumulative on repeated exposure, dogs were exposed to two episodes of +Gz stress separated by a three-minute recovery period. Blood gas status during the last 20 seconds of each 60-second exposure was assessed. Results indicated that the same degree of detriment occurred during both exposures. Pig chest wall shape and compliance is closer to man's than is the dog chest wall.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1982
- Accession Number
- ADA122297
Entities
People
- Harold I. Modell